Screw-driver.



A. KREMER.

SCREW DRIVER.

APPLICATION FILED JAN. 13. 1915.

1,230,173. Patented June 19, 1917,

2 SHEETS-SHEET I.

A. KREMER.

SCREW DRIVER.

APPLICATION FILED IAN. I3. I915- Y Patented June 19, 1917.

' 2 SHEETS-SHEET 2.

ADOLPH KREMEB, 015 NEW YORK, N. Y.

SCREW-DRIVER.

Specification of Letters Patent.

Patented June ta, i917.

Application filed. January 13, 1915. Serial No. 1,981.

3 5 the county and State of New York, have in-, vented a new and Improved Screw-Driven.

of which the following is a full and exact description.

In turning a screw driver, it is difficult to keep its axis in line with that of the screw to which it is applied. Consequently its chisel-end is liable to escape from the notch of the screw.

My invention relates to the construction of a screw driver by which these difliculties are corrected.

For this purpose I make the blade of a screw driver so. it will move within a slot of the shank, which motion, with the rocking motion of the chisel-end in the notch of the screw, acts, as it were, on a spherical joint.

Another feature of my screw driver is that it can be operated in a limited angle to the axis of a screw.

Another feature of my invention is the construction of a screw driver I whereby blades with chisel-ends of different width, thickness and shape as well as broken blades, can be quickly attached and detached.

A further feature of my invention is its detachability for use on automatic screw drivers.

Additional objects of my invention will appear in the following complete specifications in which its preferences will be de-' scribed.

In the drawings similar characters of reference indicate corresponding parts in all views in which- 40 Figure 1 is a vertical section showing one form of my improved screw driver;

Fig. 2 is a similar view of a modification;

Fig. 3 is a vertical section of the modification shown in Fig. 2 at right angles to at right angles to each other of a fourth modified form of screw driver.

Referring to the drawings and particularly Fig. 1 a indicates the shank of the screw driver consisting of the usual round metal rod with the lower end of the shank enlarged somewhat into generally rectangular cross section.

The blade I) of the screw driver which is shown detached in Fig. 4 projects at its upper'end into a slot in the lower end of the shank and is pivotally supported at the lower end of the shank by means of trunions working in bearings Z in the shank of the screw driver on each side of the slot. The 70 bearings Z and trunnions 7c are somewhat more-than half a circle in extent so that when the blade of the screw driver is positioned to form an axial extension of the shank it will be held in its bearings. Whenhowever the blade is turned to a sufiicient angle to the shank it may be detached as will be obvious froman inspection of Fig. 10. To hold the blade against accidental detachment and also to prevent too free oscillation when the screw driver is in use, the upper edge of the blade is provided with a notch over the center of the trunnions into which projects the end of the pin 0 mounted in a central bore in the shank of the screw driver and pressed against theblade by a spring 0!. The edges of the notch are curved as shown to provide a surface which will force the pin back against the tension of the spring when the screw driver blade is turned in its bearings. 9

The construction so far described is common to the modifications shown in Figs. 1

to 10 inclusive. In the construction shown in Figs. 1 and 4 the pressure spping is relied upon to prevent the withdrawal of the blade. In the form shown in Figs. 2, 3, 5, and 6 I provide an additional construction to positively lock the blade against turning beyond a certain angle. For this purpose the edges of the notch in the top of the blade near the top of the convex projections on each side of the notch are provided with shoulders 92?. adapted to engage the side of the pir. 0 to hold the blade against pivotal movement sufficient to be withdrawn from its bearings. In order however that the blade may be detached for renewal or substitution of a' different size blade, I provide on one side a small bore n leading from the outer edge of the blade to a point in the wallofa notch 1 45 against the screw.

in advance of the shoulder m whereby a suitable pin, such as shown at h, Fig. 2, may be thrust into a bore to press against the end of the pin and elevate the pin 0 to clear the shoulder and to permit detachment of the blade.

The pin 71, may be provided as shown in the drawing with a screw threaded head whereby it may be set in a socket in the head of the screw driver handle.

Inthe modification shown in Figs. 7, 8 and 9 the blade is locked against excessive motion by means of a pin 6 mounted( in a cross bore in the shank-of the screw driver intersecting the top of the slot in which the upper edge of the blade turns. A spring f holds the pin slightly projected on one side and in such a position that a portion of its lower convex face lies in the path of the projections on each side of the notch in the upper edge of the screw driver blade. The pin eis prevented from turning by the pin c-which projects through a slot in the pin 6 for permitting its transverse movement.

The pin 6 is also provided with a notch in its lower edge which is brought into registration with the blade when the pin is pressed inward against the tension of its spring. In the construction shown in Figs. 11 and 12 the blade I) is provided with a circumferen ti'al enlargement operating in a suitable socket in the end of the shank a and is held against excessive oscillation by means of a cross pin 9 projecting through the shank and through the slot in the upper edge of the blade.

The method of using my improved screw driver and its advantages will be apparent from the construction shown in the draw- 40 ings as the blade is virtually held in its "central position with suflic'ient pressure to resist the accidental side movement which happens if the blade were freely pivoted and causes it to give way under the pressure mitted is quite suflicient to accommodate any angle between the axis of the screw driver and thescrew and to prevent mutilation of the screw head. All the driving pressure comes on the trunnions which may be as large as necessary to sustain the thrust and torsion of driving the screw.

Having described my invention, I claim as new and desire to secure by Letters Patcut:

1. In a screw driver, a shank, a blade pivotally attached to the end of said shank and detachable from said shank upon pivotal movement beyond a predetermined extent, a yielding member carried by said shank and engaging said blade to yieldingly hold it in alinement with said shank but permitting a pivotal movement of the blade to an extent somewhat less than necessary to detach said blade from said shank, said The movement per-.

blade and 'said member'having cooperating parts shaped to engage and resist movement of the blade beyond said permitted movement.

2. In a screw driver, a shank, a screw driver blade in the end of said shank and detachable therefrom upon pivotal move ment beyond a" predetermined extent, means for releasably and positively limiti the angular movement of said blade to less than such predetermined extent, and for noryieldingly in a1inev 4. In a screw driver having a' slotted shank, a blade pivoted in the end of said screw driver, said blade having an -exten'-' sion lying in said slot, a yielding member mounted in said shank and engaging said extension to yieldingly. hold .the blade against angular movement said yielding member and extension having cooperating parts arranged to engage after a predetermined pivotal movement of the blade away from its position of alinement and resistfurther movement. 7 Y I I 5. In a. screw driver, a shank, a blade pivotally mounted in the end of said shank,

the pivots and bearings of the blade and shank respectively being shaped to permit detachment of the blade when turnedbeyond a predetermined distance from a position of the shank, and means for yieldingly holding said-blade against angular .movement from said position, said blade and said means having cooperative parts arranged to engage after a predetermined movement of the blade from its position of alinement less than the movement necessary to detach the blade and resist further movement of the blade.

6. In a screw driver, a shank, a blade pivotally mounted in the end of said shank, the ivots and bearings of the blade and shan respectively being shaped to permit detachment of the blade when turned beyond a predetermined distance from the I normal position with-the edge of the blade at right angles to the axis of the shank,-a locking device for preventing movement of the blade beyond such predetermined angle,

angular said locking means permitting movement within such angle w 1 0 ing position.- y

.. In a screw driver, a shank having a slottedend, a blade in said slot, trunnionsin lockrojecting' from the opposite faces of said I lade, the ends of said slotted shank being provided with bearings for said trunnions, said bearings being open on the lower edge through .an angular distance less than 180 and said trunnions being cut away on their lower face to present a transverse dimension of less extent than the open lower edge of the shank bearings, while retaining a full 180 pressure receiving surface upon the upper half of the trunnion.

.8. In a screw driver,a shank having a slotted end, ablade in said slot, trunnions projecting from the opposite faces of said blade, the endsof said slotted shank' being provided with bearings for said trunnions, said bearings being open on the lower edge through an angular distance less than 180 and said trunnions being cut away on their lower face whereby the blade may be released from the shank when angularly turned beyond a predetermined extent, and locking means permitting while in looking position angular movement of the blade within such extent, but preventing movement beyond such angular extent until positively released.

9. In a screw driver, a shank having a slotted end, a blade pivotally mounted in said slot, the upper edge of said blade being shaped to present a central depression with cam faces rising on each side of said depression, a spring-pressed pin engaging the edge of said blade tohold the same yieldingly in alinement with the axis of the shank, and

stops formed on said blade at the outer edges of said cam faces for positively preventing rotation of the blade beyond a predetermined extent.

In testimony whereof, I have signed my name to this application in the presence of two subscribing witnesses.

ADOLPH KREMER.

Witnesses:

ALEXANDER KANN, BENJ SOLOMON. 

